It's important to note that you don't actually buy e-books from Amazon, you license the right to read, and when that license is revoked/cancelled, those books are no longer available to you.
http://www.eurogamer.net/articles/2012-07-03-eu-rules-publis...
Being banned from Google, Amazon & others for sometimes very fuzzy reasons can be major inconvenient. Sure, it's not a human right or a life or death situation, but they occupy dominant space on their markets and on some people life.